AW: [Insight-users] Inversion of transformation fields

[Floca, Ralf]

Hi Luis,

Thank You, for your quick repsonse and the solution.

Must have been blind, that i missed this filter in the documentation. So thanks for the guidance.

Regards,
Ralf

-----Ursprüngliche Nachricht-----
Von: Luis Ibanez [mailto:luis.ibanez at kitware.com] 
Gesendet: Freitag, 4. März 2005 15:46
An: Floca, Ralf
Cc: insight-users at itk.org
Betreff: Re: [Insight-users] Inversion of transformation fields


Ralf,

There is also an iterative implementation....

http://www.itk.org/Insight/Doxygen/html/classitk_1_1IterativeInverseDeformationFieldImageFilter.html


Regards,


    Luis


----------------------
Floca, Ralf wrote:

> Hello everyone.
> 
> I am working on different registration approaches. Some of them 
> consists of more then one registration steps (e.g. rigid 
> preregistration and non rigid registration). All of them are data 
> driven, so working directly on the image. But in some cases, there are 
> some additional information like reference points (e.g. fiducals) 
> attached. To keep them up to date through out the whole registration 
> process, they also must be transformed. Now the problem. ITK uses back 
> transform to ensure dense images. This is appropriate for the 
> registration of the image itself, but to transform meta information 
> (like reference points, to have them up to date in interim 
> registration steps) a transform from moving to result image is needed. 
> In cases of a rigid registrations I could use the back transform 
> function for every single point to achieve this. But the fem, for 
> example, only produces a transformation field and has no back 
> transform or inversion capabilities. Are there any suitable methods to 
> invert this field to achieve a transform of points from the moving 
> image space to the result image space?
> The easy way: inverting all vectors of the field would only be a
> solution, if the spacing was infinitesimal (whish it was so). So this
> would be no solution.
> 
> I am thankful for every reply and comments.
> 
> Thanks and best regards,
> Ralf o Floca
> 
> ---------------------------------------------------------------------
> Ralf Floca
> University of Heidelberg                           
> Institute for Medical Biometry and Informatics
> Department of Medical Informatics
> Im Neuenheimer Feld 400            
> D-69120 Heidelberg, Germany             Tel. : 06221/56-7484  
> http://www.med.uni-heidelberg.de/mi     Fax  :         -4997    
> ralf_floca at med.uni-heidelberg.de        Sekr.:         -7483
> ---------------------------------------------------------------------
> 
>  
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